tests: Add timeout to .gunittest.cfg file

[echoix]

Also to address a part of #1312.

Adding a default timeout value to .gunittest.cfg in grass-addons too, like for the main repo.

5 minutes is probably not enough because some tests are really long, but I want to see which ones are timing out on the CI runners speed first.

Even though #1314 limited the test step to 45 minutes, the r.futures.calib apparent hang already happens after 7 minutes, so there's almost 40 minutes spent waiting on timing out.

[wenzeslaus]

Thanks!

[echoix]

At least for now its getting further..

[echoix]

I compared the two test reports, with an older one, and two of previously passing tests that were timing out here were just close to the limit.

For example, ./temporal/t.rast.import.netcdf – test_t_rast_import_netcdf already passed in 4:49, and ./raster/r.viewshed.exposure – test_r_viewshed_exposure passed in 5:05.
In that same 3.11 passing test report, when ./raster/r.futures/r.futures.calib – test_r_futures_calib passes, it takes 0:17.45 (17.45 seconds)